Abstract: | The kinetics of dimethyl sulfoxide (DMSO) oxidation by peroxomonophosphoric acid (PMPA) in aqueous medium at 308 K and I = 0.4 mol/dm3 follow the rate expressions In the pH range from 0 to 2, where k1 and k2 are 5.092 × 10?1 dm3/mol sec and ? 0, respectively; in the pH range from 4 to 7, where k2 = 8.127 × 10?3 and k3 = 2.90 × 10?3 dm3/mol sec; and in the pH range from 10 to 13.6, where k4 ? 0, and k5 = 3.08 × 10?2 dm3/mol sec. The reaction is interpreted in terms of mechanisms involving an electrophilic and a nucleophilic attack of the peroxomonophosphoric acid species, respectively, in acid and alkaline regions, on the sulfur atom of the sulfoxide molecule giving rise to S-type transition states followed by oxygen-oxygen bond fission to form the products. |